Cleaning solutions including nucleophilic amine compound having reduction and oxidation potentials

ABSTRACT

A composition for removing resists and etching residue from substrates containing at least one nucleophilic amine compound having oxidation and reduction potentials, at least one organic solvent, water and, optionally, a chelating agent is described. The chelating agent is preferred to be included since it provides added stability and activity to the cleaning composition so that the composition has long term effectiveness. If a chelating agent is not present, the composition, while providing for adequate stripping and cleaning upon initial use of the composition following mixing, has only short term stability. In this latter instance, the nucleophilic amine compound and organic solvent components of the composition preferably are maintained separate from each other until it is desired to use the composition. Thereafter, the components are combined. Following use of the composition, the non-used portion of the composition can be disposed of or be reactivated by the addition of a chelating agent.

RELATED PATENT APPLICATIONS

The present invention is a continuation-in-part of U.S. patentapplication Ser. No. 07/911,102 filed Jul. 9, 1992 entitled “CleaningCompositions for Removing Etching Residue and Method of Using”, which inturn is a continuation-in-part of U.S. patent application Ser. No.07/610,044 filed Nov. 5, 1990 entitled “Stripping CompositionsComprising Hydroxylamine and Alkanolamine.

FIELD OF THE INVENTION

The present invention is directed to resist and etching residue removingcompositions comprising at least one nucleophilic amine compound whichpossesses reduction and oxidation potentials, at least one organicsolvent which is miscible with the nucleophilic amine, water and,optionally, one or more chelating agents. The solutions are useful inremoving resists and etching residue from micro-circuitry duringfabrication processes.

BACKGROUND OF THE INVENTION

During the fabrication of microcircuits, the precise positioning of anumber of appropriately doped regions on a slice of semiconductor isrequired followed by the positioning of one or more interconnectionpatterns on the semiconductor. Positive-type resists have beenextensively used as masking materials to delineate patterns onto asubstrate so that the patterns can be subsequently etched or otherwisedefined into the substrate. The final steps in preparing the substratethen involve removing the unexposed resist material and any etchingresidue from the substrate. Increasingly, however, plasma etching,reactive ion etching or ion milling is used to define the pattern in asubstrate which renders the resist mask substantially impossible toremove by stripping agents heretofore commonly used for such or similarpurposes containing one or more of the following solvents: halogenatedhydrocarbons such as, for example, methylene chloride ortetrachloroethylene; amines and their derivatives such as, for example,dimethylformamide, dimethylacetamide, pyrrolidone, diethanolamine, andtriethanolamine; glycol ethers, such as, for example, ethylene glycolmonoethyl ether, 2-butoxyethanol, and 2-(butoxy-ethoxy)ethanol; and analkylsulfone, such as, for example, dimethylsulfone.

Additionally, during such etching processing, an organometallicby-product compound can be formed on the sidewall of the substratematerial. The above-mentioned solvents are also ineffective in removingsuch organometallic polymers. A recently developed technique effectivefor photoresist removal is plasma oxidation, also known as plasmaashing. However, while this process is effective for removing aphotoresist, it is not effective for removing the organometallic polymerformed on the sidewall of the substrate during the etching process.

Further, polyimides are increasingly used in microelectronics asfabrication aids, passivants, and inter-level insulators. The use of apolyimide as a fabrication aid includes application of the polyimide asa photoresist, planarization layer in a multi-level photoresist schemeand as an ion implant mask. In these applications, the polymer isapplied to a wafer or substrate, subsequently cured or patterned by asuitable method and removed after use. Many conventional strippers arenot sufficiently effective in removing the polyimide layer once thepolyimide has been subjected to a severe curing operation. The removalof such polyimides is normally accomplished by boiling the substrate inhydrazine or in oxygen plasma.

Accordingly, a composition suitable for stripping a resist so as toremove the resist rapidly and completely would provide substantialadvantages over conventional strippers. Further, a composition capableof removing both the resist and organometallic by-products would provideeven a greater advantage. As apparent, if an etching residue is notcompletely removed from the substrate, the residue can interfere withsubsequent processes involving the substrate.

In addition to removing completely the resist material, particularlywith the introduction of submicron process techniques to form wafers,there is a demand for cleaning technology for removing etching residueremaining following resist removal. The requirement for a cleaningsolution to remove all types of residue generated as a result of plasmaetching of various types of metals, such as aluminum,aluminum/silicon/copper, titanium, titanium nitride, titanium/tungsten,tungsten, silicon oxide, polysilicon crystal, etc., presents a need formore effective cleaning chemistry in the processing area.

More specifically, during the fabrication of microcircuits, thesubstrate surface can be aluminum, titanium, silicon oxide orpolysilicon and patterns are delineated thereon by chemical etching.Increasingly, plasma etching, reactive ion etching or ion milling areused, and such etching processes produce undesirable by-products fromthe interaction of the plasma gases, reacted species and thephotoresist. The composition of such by-products is generally made up ofthe etched substrates, underlying substrate, photoresist and etchinggases. The formation of such by-products is influenced by the type ofetching equipment, process conditions and substrates utilized. Theseby-products are generally referred to as “sidewall polymer,” “veil”,“picket fences”, “rabbit ears” or “goat horns”, and cannot be removedcompletely by either oxygen plasma or conventional solvents, such asN-methyl-2-pyrrolidone, diethyleneglycolmonobutyl-ether,dimethylacetamide or the like, which are conventionally used to removeresists. It is critical that all of the etching residue and the like beremoved to provide a wafer having sufficient integrity for subsequentuse of the wafer in microcircuitry.

Examples of alkaline/solvent mixtures useful as photoresist strippers,but not necessarily cleaners, known for use in stripping applicationsinclude dimethylacetamide or dimethylformamide and alkanolamines asdescribed in U.S. Pat. Nos. 4,770,713 and 4,403,029; 2-pyrrolidone,dialkylsulfone and alkanolamines as described in U.S. Pat. Nos.4,428,871, 4,401,747, and 4,395,479; and 2-pyrrolidone andtetramethylammonium hydroxide as described in U.S. Pat. No. 4,744,834.Such stripping compositions, however, have only proven successful incleaning “sidewall polymer” from the contact openings and metal lineetching in simple micro-circuit manufacturing involving a single layerof metal when the metal structure involves mainly Al—Si or Al—Si—Cu andthe “sidewall polymer” residue contains only an organometallic compoundwith aluminum. The cleaning mechanism involving such materials has beenstudied by EKC Technology, Inc. and Intel Corp., as presented at theK.T.I. Conference in 1989 in the presentation entitled “Metal Corrosionin Wet Resist Stripping Process,” by P. L. Pai, C. H. Ting, W. M. Leeand R. Kuroda. Due to the corrosive nature of such strippers as abovedescribed, the “sidewall polymer” is removed either by attacking theorganoaluminum compound or the metal surface itself and causing the“sidewall polymer” residue to be lifted off. Further, in addition to theuse of the stripping composition, mechanical scrubbing, such asultrasonic vibration, is required to achieve complete removal of the“sidewall polymer.”

The most current submicron processing techniques utilized in theindustry involving multi-levels of metal and multi-level ofinterconnecting processes usually incorporate metal materials includingTiN, TiW, Ti, TiSi, W, WSi and the like. The use of such materialsresults in the generation of new organometallic material by-productsduring plasma etching, whether formed intentionally or unintentionally,which renders the cleaning incomplete when utilizing existingcommercially available stripping and cleaning products. Such findingswere described at the SPIE Symposium on Microlithography in 1991 in apresentation entitled “Plasma Etching and Reactive Ion Etching” by JohnW. Coburn. In particular, it has been found that the residue remainingon the substrate surface after removal of a resist by plasma ashing haschanged from the organometallic to the corresponding oxide, such asTiO₂, which is chemically inert to mild alkaline strippers. The effectof such poor cleaning results in low device yield, low devicereliability, and low device performance.

Therefore, conventional stripping compositions are ineffective inremoving sidewall organometallic and other metal oxide residue which ispresent following use of the current technology to remove resists. Evenplasma ashing, which has been found effective for removing photoresists,is not effective for removing the sidewall organometallic polymer andsome other of the metal oxide residues formed during etching processes.

OBJECTS OF THE INVENTION

Accordingly, a primary object of the present invention is to provide aresist and etching residue removing composition comprising at least onenucleophilic amine compound which possesses oxidation and reductionpotentials, at least one solvent which is miscible with the nucleophilicamine compound; water, and optionally, one or more chelating agents; anda method of using the composition to completely remove a resist andclean a microcircuitry substrate.

A further primary object of the present invention is to provide a resistand etching residue removing composition having long term stability byproviding a composition comprising at least one nucleophilic aminecompound possessing reduction and oxidation potentials, at least onesolvent which is miscible with the nucleophilic amine compound, water,and at least one chelating agent.

A further primary object of the present invention is to provide a resistand etching residue removing composition including at least onenucleophilic amine compound possessing reduction and oxidationpotentials, at least one solvent which is miscible with the nucleophilicamine compound, and water, wherein the nucleophilic amine and theorganic solvent are maintained separately and combined just prior to useand which is disposable after use due to having a short active lifecycle. Alternatively, this composition, once formed by combining thecomponents as identified above, can be reactivated by combining achelating agent therewith.

A further primary object of the present invention is to provide acomposition for removing residue formed during etching and resistremoval processes from a substrate without adversely damaging thesubstrate surface or hindering subsequent operation or process stepsinvolving the substrate.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is directed to a resist and etching residueremoving composition comprising at least one nucleophilic amine compoundhaving oxidation and reduction potentials, at least one organic solventwhich is miscible with the nucleophilic amine compound, water and,optionally, one or more chelating agents. The water can be added to thecomposition by itself or as a carrier for the nucleophilic aminecompound, i.e., the nucleophilic amine is present in aqueous solution.

Related application U.S. Ser. No. 610,044 filed Nov. 5, 1990, which isincorporated herein by reference and which corresponds to publishedEuropean Patent Application No. 485,161 A1, discloses hydroxylamine incombination with an alkanolamine which is miscible with thehydroxylamine as being useful to remove a resist from a substrate. Ithas now been found that compounds other than hydroxylamine and analkanolamine are useful for removing resists, but in particular are alsouseful in removing etching residues from substrates. It has been foundthat nucleophilic amine compounds having oxidation and reductionpotentials satisfactorily remove resists and etching residue from asubstrate when combined with an organic solvent which is miscible withthe nucleophilic amine compound and water. While the nucleophilic aminecompound must have the potential for reduction and oxidation, it is notrequired that reduction and oxidation actually occur in the use of thecomposition. Examples of nucleophilic amine compounds useful in thepresent invention include hydroxylamines, hydrazines, certain specifiedanines, and their derivatives as further described below. The organicsolvent is not required to be an amine, but the presence of an aminesolvent is preferred.

Further, it has been found that when a chelating agent is present in anaqueous solution containing at least one nucleophilic amine compoundhaving reduction and oxidation potentials and an organic solvent whichis miscible with the nucleophilic amine compound that at least twoadditional surprising benefits are achieved, namely, (1) the chelatingagent assists in cleaning by retaining etching residue in the cleaningsolution and thereby avoiding resettling of the residue onto thesubstrate and (2) the chelating agent serves as a stabilizing agent toprovide long term effectiveness to the composition. More specifically,the chelating agent enhances the cleaning capability of the compositionby retaining or “freezing” the etching residue in the cleaning solutionafter the nucleophilic amine compound has picked up the residue from thesubstrate. This action minimizes resettling of any residue onto thesubstrate. The presence of the chelating agent further provides thecomposition with long term activity and, therefore, a long shelf life.When a chelating agent is not present in the aqueous solution of anucleophilic amine compound and organic solvent, the solution has onlyshort term stability, i.e., generally an active life of about one week.Accordingly, when a chelating agent is not present, it is preferable tomaintain the nucleophilic amine compound and organic solvent separatelyuntil just prior to use. After the components are combined and thesolution used, the remaining solution can be disposed of or, once theactivity has decreased, the solution can be reactivated by the additionof a chelating agent. Preferred chelating agents are dihydroxybenzenesand their derivatives as further described below.

The cleaning composition is especially useful in removing etchingresidue from substrates which contain metal elements other than aluminumsuch as titanium (Ti), tungsten (W), silicon (Si) and silicon oxide(SiO₂). While the compositions of the invention are capable of removingresists from substrates, the compositions of the invention have beenshown to have a surprising capacity for cleanly removing etchingresidue, in particular organometallic and metal oxide etching residue,from a substrate surface following removal of a resist therefrom.Currently in the industry, etching residue is extremely difficult tocompletely remove without damaging the substrate.

The cleaning compositions of the present invention are particularlysuitable for removing organometallic and metal oxide residues from asubstrate, in particular, during the fabrication of a submicron (i.e.,less than 0.8 microns) integrated circuit without adversely affecting orhindering subsequent manufacturing operation or process steps involvingthe substrate. Further, the cleaning compositions of the invention areeffective in removing organometallic residue outgasing which has beendeposited on parts of the etching equipment utilized in the processing.This equipment can be made of polycarbonate, ceramic or aluminum.

The method of removing a resist or etching residue from a substrateusing the compositions of the present invention also is advantageous inthat complex process steps and equipment are not required. The method ofthe invention involves contacting a substrate containing a resist oretching residue with the composition of the invention as describedherein at a temperature and for a time sufficient to remove theparticular resist or etching residue present.

DESCRIPTION OF THE DRAWING

FIG. 1 shows etched wafer residue following the use of plasma ashing toremove a resist from a silicon oxide dielectric layer which had beenearlier plasma etched.

FIG. 2 shows the results of an analysis using ion mass spectrometry(LIMA) of the residue shown in FIG. 1. Such analysis indicates that theresidue contains metal oxide and trace amounts of organic material.

FIGS. 3A and 3B show the results of a comparison test utilizing acleaning composition of the present invention (FIG. 3A) and a strippingcomposition as described in U.S. Pat. No. 4,403,029 (FIG. 3B) inrelation to a silicon oxide dielectric layer containing etching residuethereon which is present following removal of a resist by plasma ashing.By comparing FIG. 3A with FIG. 3B, it can be seen that all theorganometallic residue was removed using the composition of the presentinvention while residue remained following use of the strippingcomposition described in U.S. Pat. No. 4,403,029.

FIGS. 4A and 4B show the results of a comparison test utilizing acleaning composition of the present invention (FIG. 4A) and a strippingcomposition as described in U.S. Pat. No. 4,770,713 (FIG. 4B) inrelation to a silicon dielectric layer which contained etching residuefollowing removal of a resist therefrom by plasma ashing. As evidentupon a comparison of FIG. 4A with FIG. 4B, the composition of thepresent invention removed all the organometallic residue while the othercomposition did not.

FIG. 5A shows a microcircuit pattern of polysilicon over silicon oxidecontaining etching residue which remained on the substrate followingplasma etching. FIG. 5B shows the same microcircuit pattern followingcleaning with a composition of the present invention. As evident from acomparison of FIG. 5A with FIG. 5B, it can be seen that the residue hasbeen removed.

FIG. 6A shows residue which remained on a metal substrate after theremoval of a photoresist from the substrate by plasma ashing. FIG. 6Bshows the same substrate following cleaning with a composition of thepresent invention.

FIGS. 7A-7D show the results of comparison tests using a cleaningcomposition of the present invention (FIGS. 7A and 7B) and aN-methyl-2-pyrrolidone solvent/-alkanolamine base stripper (FIGS. 7C and7D) in relation to openings on a silicon oxide dielectric layer. Asshown in FIGS. 7A and 7B, all the organometallic residue was removedusing the composition of the present invention while, as evident fromFIGS. 7C and 7D, residue remained on the substrate treated with thestripper.

FIG. 8A shows residue remaining on a wafer following etching and theremoval of a photoresist therefrom. FIG. 8B shows the same waferfollowing cleaning with a composition of the present invention. All theresidue on the wafer was removed.

FIG. 9 illustrates the results of Example 11 below wherein the stabilityof cleaning Compositions A, C and G were compared.

DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENT

The cleaning and stripping composition of the present invention forremoving etching residue and resists from a substrate contains at leastone nucleophilic amine compound having oxidation and reductionpotentials in a cleaning environment, at least one organic solvent whichis miscible with the nucleophilic amine compound, water, and,optionally, one or more chelating agents. The water can be provided inthe composition independently or in combination with the nucleophilicamine compound, for example the nucleophilic amine compound can be addedas a_(—)50% aqueous solution.

In a composition according to the invention, the composition preferablycontains a chelating agent. The chelating agent serves to provide longterm stability and activity to the composition. The composition,therefore, has the desirable commercial attribute of having a long shelflife.

Alternatively, the composition can be provided including at least onenucleophilic amine compound having reduction and oxidation potentials,an organic solvent and water. This composition, however, only has shortterm effectiveness and so it is preferable that the nucleophilic aminecompound and organic solvent are maintained separate until just prior touse. As stated above, the water can be present in combination with thenucleophilic amine compound. In this case the nucleophilic aminecompound in aqueous solution will be maintained separate from theorganic solvent until just prior to use. The components are thencombined and the composition used as needed. Generally, the compositionwithout a chelating agent will have an effective active life forapproximately one week. Any unused portion of the composition can thenbe simply disposed of or, alternatively, the unused portion can bereactivated by the addition of a chelating agent to the solution.

The composition of the invention can be used as a stripping compositionto remove a resist or a cleaning composition to remove etching residuefrom a substrate. The ability to remove etching residue effectively isin particular surprising in view of the difficulty experienced in theart to produce an effective etching residue removing solution.

The cleaning compositions of the present invention are suitable forremoving etching residue, such as organometallic and metal oxideresidue, formed on a substrate, in particular residue formed duringplasma etching processes. The substrate can include aluminum andnon-aluminum metal elements such as titanium, tungsten, silicon andsilicon oxide. The extent and type of residue remaining followingetching is determined by the etching equipment utilized, processconditions and substrates utilized.

The cleaning composition preferably includes from about 5% to 50% byweight of at least one nucleophilic amine compound having reduction andoxidation potentials, from about 10% to 80% by weight of at least oneorganic solvent which is miscible with the nucleophilic amine compound,optionally from about 5%-30% by weight of at least one chelating agent,and with the remaining balance of the composition being made up ofwater, preferably high purity deionized water.

Compounds suitable for use as the nucleophilic amine compound havingoxidation and reduction potentials include certain amines,hydroxylamines, hydrazines and their derivatives as set forth below. Thenucleophilic amine compound used in the present invention does not haveto actually take part in oxidation or reduction during a cleaning orstripping process. The nucleophilic amine compound must only possessoxidation and reduction qualities in a cleaning or strippingenvironment. Suitable nucleophilic amine compounds useful in the presentinvention are compounds having the following formula:

wherein R₁, R₂, R₃ and R₄ are either the same or different and selectedfrom the group including hydrogen; a hydroxyl group; a substituted C₁-C₆straight, branched or cyclo alkyl, alkenyl or alkynl group; asubstituted acyl group; a straight or branched alkoxy group; an amidylgroup; a carboxyl group; an alkoxyalkyl group; an alkylamino group; analkyl sulfonyl group; or a sulfonic acid group; x=O when y=1 or x=O or 1when y=O; y=O when x=1 or y=O or 1 when x=O; provided R₄ is present onlywhen x=1; or salts thereof. Specific examples of nucleophilic aminecompounds are further described below.

Hydroxylamines suitable for use as the nucleophilic amine compoundhaving reduction and oxidation potentials are represented by thefollowing formula:

wherein R₁, R₂, and R₃ are independently hydrogen; a hydroxyl group;optionally a substituted C₁-C₆ straight, branched or cyclo alkyl,alkenyl, or alkynyl group; optionally a substituted acyl group, straightor branched alkoxy group, amidyl group, carboxyl group, alkoxyalkylgroup, alkylamino group, alkylsulfonyl group, or sulfonic acid group, orthe salt of such compounds. Derivatives of these compounds, for examplethe amides of the above described, are also suitable for use.

Amines suitable for use as the nucleophilic amine compound of theinvention can be represented by the following formula:

wherein R₁, R₂, and R₃ are independently hydrogen; optionally asubstituted C₁-C₆ straight, branched or cyclo alkyl, alkenyl, or alkynylgroup; optionally a substituted acyl group, straight or branched alkoxygroup, amidyl group, carboxyl group, alkoxyalkyl group, alkylaminogroup, or alkylsulfonyl group, sulfonic acid group; or the salt of suchcompounds.

Hydrazines suitable for use as the nucleophilic amine compound of thepresent invention can be represented by the following formula:

wherein R₁, R₂, R₃, and R₄ are independently hydrogen; a hydroxyl group;optionally a substituted C₁-C₆ straight, branched or cyclo alkyl,alkenyl, or alkynyl group; optionally a substituted acyl group, straightor branched alkoxy group, amidyl group, carboxyl group, alkoxyalkylgroup, alkylamino group, alkylsulfonyl group, or sulfonic acid group: orthe salts of such compounds.

The preferred nucleophilic amine compounds having reduction andoxidation potentials are alkoxy substituted amines, hydroxylamine, alkylor carboxyl substituted hydroxylamine, and alkyl or carboxyl substitutedhydrazine. The most preferred compounds are hydroxylamine,N-methylhydroxylamine hydrochloride, N,N-diethylhydroxylamine, andmethylhydrazine.

Organic solvents suitable for use in the present invention are misciblewith the nucleophilic amine compound and are preferably water-soluble.Additionally, the organic solvent useful in the present inventionpreferably has a relatively high boiling point, such as for example 100°C. or above, and a high flash point, such as for example 45° C. orabove.

Suitable organic solvents include alkanolamines and their derivatives.Additionally, non-amine solvents, such as dimethyl sulfoxide (DMSO), aresuitable for use. Preferably an amine solvent is present alone or incombination with another solvent. Previously, it had been believed thatan alkanolamine solvent had to be utilized. While an alkanolaminesolvent is still a preferred solvent, it has now been found that othersolvents are suitable for use when utilized with at least onenucleophilic amine compound having reduction and oxidation potentials.

Suitable alkanolamines are primary, secondary or tertiary amines and arepreferably monoamines, diamines or triamines, and, most preferably,monoamines. The alkanol group of the amines preferably has from 1 to 5carbon atoms.

Preferred alkanolamines suitable for use in the present invention can berepresented by the chemical formula R₁R₂—N—CH₂CH₂—O—R wherein R₁ and R₂can be H, CH₃, CH₃CH₂, or CH₂CH₂OH and R₃ is CH₂CH₂OH.

Examples of suitable alkanolamines include monoethanolamine,diethanolamine, triethanolamine, tertiarybutyldiethanolamineisopropanolamine, 2-amino-1-propanol, 3-amino-1-propanol,isobutanolamine, 2-amino-2-ethoxy-propanol, and2-amino-2-ethoxy-ethanol, which is also known as diglycolamine.

Additional examples of organic solvents suitable for use in thecomposition of the present invention include N-methyl-2-pyrrolidinone,N,N-dimethylpropanamide, N,N-diethylformamide, ethylene glycol, ethyleneglycol alkyl ether, diethylene glycol alkyl ether, triethylene glycolalkyl ether, propylene glycol, propylene glycol alkyl ether, dipropyleneglycol alkyl ether, tripropylene glycol alkyl ether, N-substitutedpyrrolidone, ethylenediamine, and ethylenetriamine. Additional polarsolvents as known in the art can also be used in the composition of thepresent invention.

Preferred chelating agents useful in the composition of the inventionare hydroxybenzenes according to the formula—

wherein n=1-4, m=2-5 and R is independently hydrogen, optionally asubstituted C₁-C₆ straight, branched or cyclo alkyl, alkenyl, or alkynylgroup; optionally a substituted acyl group, straight or branched alkoxygroup, amidyl group, carboxyl group, alkoxyalkyl group, aklylaminogroup, alkylsulfonyl group, or sulfonic acid group; or the salt of suchcompounds. The preferred compounds are the dihydroxybenzene isomers, andthe alkyl substituted dihydroxybenzenes. The most preferred compoundsare 1,2-dihydroxybenzene and 1,2-dihydroxy-4-t-butylbenzene.

Additional chelating agents as known in the art can also be used in thecomposition of the present invention. For example, chelating agentswhich are metal ion free chelating agents can be utilized, such asthiophenol and its derivative according to the formula—

where R₁═OH or COOH; or ethylene diamine tetracarboxylic acid, of theformula—

wherein R₁, R₂, R₃ and R₄ can be either H or NH₄, and its ammonium salt.Sodium, potassium or the like salts are not believed to be suitable foruse based upon the understood mechanism of ionic contamination in amicrocircuit as caused by cleaning. As evident from the above formula,the carboxylic acid can be mono-, di- or tri-substituted rather thantetra-substituted.

Additional suitable chelating agents include alkyl ammonium hydroxideswhich can be represented by the formula R₁R₂R₃R₄NOH wherein R₁, R₂, R₃,and R₄ are short chain alkyl groups, preferably having from 1 to 5carbon atoms, and wherein R₁, R₂, R₃, and R₄ can be the same ordifferent. A preferred alkyl ammonium hydroxide is tetramethylammoniumhydroxide.

A presently most preferred cleaning composition of the inventioncomprises, based on the total weight of the composition, 35 partshydroxylamine, 65 parts 2-amino-2-ethoxyethanol, and 5 parts1,2-dihydroxybenzene, wherein the hydroxylamine is present as a 50%aqueous solution. Other preferred specific embodiments are set forth inthe examples below.

Examples of substrates from which the stripping and cleaningcompositions of the present invention remove photoresists withoutattacking the substrates themselves include metal substrates such asaluminum, titanium/tungsten, aluminum/silicon, aluminum/silicon/copper;and substrates such as silicon oxide, silicon nitride, andgallium/arsenide; and plastic substrates such as polycarbonate.

The cleaning compositions of the present invention are also effective inremoving etching residue from etching equipment utilized in etchingsubstrates. Examples of commercially available etching equipment includeLam Research, Tegal, Electrotech, Applied Material, Tokyo Electron,Hitachi and the like.

The method of removing a resist from a substrate or cleaning etchingresidue from a substrate using the compositions of the present inventioninvolves contacting a substrate having a material to be removed with acomposition of the present invention for a time and at a temperaturesufficient to remove the residue. The substrate is immersed in thecomposition. The time and temperature of immersion are determined basedon the particular material being removed from a substrate. Generally,the temperature is in the range of from about ambient or roomtemperature to 100° C. and the contact time is from about 2 to 60minutes. A preferred method involves immersing a substrate sample, suchas a wafer in the solution of the invention for 30 minutes at atemperature of about 65° C. followed by placement of the substratesample in a solvent bath for 10 minutes at about 80°-85° C. and,thereafter, rinsing the substrate sample in a water bath.

Examples illustrating the removal of etching residue from a substrateare set forth below. The following examples are provided to furtherillustrate the present invention and are not intended to limit the scopeof the present invention.

In the examples, the substrate is treated in conventional known mannersprior to the treatment of the substrate with the compositions of thepresent invention.

Examples of cleaning compositions according to the present inventionutilized in Examples 1-15 below for removing etching residue from asubstrate are set forth in Table I below. TABLE I Cleaning HydroxylamineOrganic Solvent Composition Wt. % Wt. % A 25% 50% 2-Amino-2-EthoxyEthanol B 20% 60% 2-Amino-2-Ethoxy Ethanol C 20% 55% 2-Amino-2-EthoxyEthanol D 17.5%   50% Monoethanolamine E 8.75%   30% 2-Amino-2-EthoxyEthanol F 15% 60% Monoethanolamine G 15% 70% 2-Amino-2-Ethoxy EthanolCleaning Composition Water Wt. % 1,2-dihydroxybenzene Wt. % A 25% 0% B20% 0% C 20% 5% D 17.5%   15%  E 63.5%   2.5%   F 20% 5% G 15% 0%

EXAMPLE 1

Example 1 illustrates the problem of residue remaining on a wafersubstrate following plasma etching and ashing. FIG. 1 shows etched waferresidue present on an etched substrate following plasma ashing.Specifically, silicon oxide used as a dielectric layer has a patternetched for a multi-layer interconnect according to a standard plasmaetching process. A photoresist which was used as a masking material hasalready been removed by oxygen plasma ashing. Analysis of the residuepresent on the etched wafer was analyzed by ion mass spectrometry(LIMA). The results of the analysis are as shown in FIG. 2. The analysisconfirms that the residue contains metal oxide and trace amounts oforganic material.

EXAMPLE 2

Example 2 illustrates the effect of the cleaning composition of thepresent invention on a wafer as determined by C/V testing. C/V shiftmeasurement is a means utilized to determine the effect of a chemicalused to clean a wafer. A high voltage shift is mainly caused by mobileion contamination to the wafer. Such contamination will adversely affectsubsequent process steps and may eventually cause failure of themicrocircuits.

The test evaluation compares the C/V shift of different conventionalphotoresist stripping compositions to the cleaning composition of thepresent invention. All wafers used were known to be good silicon oxidesubstrates. All chemicals were heated on a hot plate to themanufacturers' suggested operating temperature using a pyrex beaker.Each of the beakers utilized was new and had not been previously used inany chemical processing. Individual beakers were used for each product.After immersing the silicon oxide wafer in the described composition,the wafers were rinsed and dried. Table II sets forth the operatingconditions and the results of the C/V shift test. TABLE II CompositionU.S. Process Product Manufacturer Pat. No. Conditions Results PRS-3000J. T. Baker 4,403,029 90° C./20 min. +15.624 volts  EMT 300 EMT4,770,713 90° C./20 min. +2.440 volts N-Methyl-2-Pyrrolidone J. T. Baker4,395,479 90° C./20 min. +2.044 volts Nophenol 944 EKC 4,395,384 100°C./20 min.  −0.368 volts Composition C — — 65° C./20 min. +0.221 voltsControl — — — −0.576 voltsA negative reading means no change in C/V shift. The cleaningComposition C according to the present invention as described above wasshown to provide a cleaner surface than any of the positive photoresiststrippers tested.

EXAMPLE 3

Example 3 illustrates the results of a comparison test betweenComposition F of the present invention as described above and thestripping composition described in U.S. Pat. No. 4,403,029 and soldunder the name PRS-2000 by J. T. Baker. The results of the comparisontest are shown with respect to an opening having the site of 1.2 micronin FIGS. 3A and 3B. Each opening was present on a silicon oxidedielectric layer which was etched using a standard silicon oxide plasmaetching process. The photoresist was removed from the layer followingetching by oxygen plasma ashing. The substrate was then processed byimmersing the substrate in Composition F as described above for 10minutes at 65° C. A micrograph from a scanning microscope as shown inFIG. 3A indicates that Composition F removed all the organometallicresidue. As shown in FIG. 3B, residue remained on the substrate when anetched wafer prepared under the same process conditions was processed byimmersion in PRS-2000 for 10 minutes at 65° C.

EXAMPLE 4

Example 4 illustrates the results of a comparison test betweenComposition C as described above and a stripping composition asdescribed in U.S. Pat. No. 4,770,713 and sold under the name ACT-150I.ACT-150I is a dimethylacetamide solvent based photoresist stripper.

The comparison test results are shown in FIGS. 4A AND 4B with respect toopenings having a size of 1.0 micron. Each opening was present on asilicon oxide dielectric layer which was etched using a standard siliconoxide plasma etching process. The photoresist was removed by oxygenplasma ashing. The substrate was then processed by immersion inComposition C as described above for 30 minutes at 45° C. A micrographfrom a scanning electron microscope as shown in FIG. 4A shows thatComposition C completely removed all the organometallic residue withoutdamaging the silicon oxide substrate. FIG. 4B shows a substrate preparedunder the same process conditions after immersion in ACT-150I for 30minutes at 45° C. As shown in FIG. 4B, the stripping composition onlypartially removed the etching residue.

EXAMPLE 5

Example 5 illustrates the cleaning of polysilicon etching residue. Amicrocircuit pattern of polysilicon over silicon oxide was etched inplasma etching equipment using HBr as an etching gas. The photoresistwas removed by oxygen plasma ashing. The etching residue, which ismostly Si—C—Br, is shown in FIG. 5A to remain on the polysilicon circuitline following the removal of the photoresist. When the wafer wasfurther processed by immersion in Composition C of the present inventionat 65° C. for 20 minutes, all of the etching residue was removed fromthe substrate as shown in FIG. 5B.

EXAMPLE 6

Example 6 illustrates the cleaning of a metal etch residue from asubstrate. A sandwich metal substrate of TiW/Al—Si—Cu/TiW was patternedand etched in a plasma metal etcher, i.e., Applied Material 8330 MetalEtcher. This metal etcher is a batch etching equipment and therefore iscapable of treating more than one wafer at a time. Due to the manner ofetching performed by such etching equipment, a lesser amount of“polymer” residue is built-up during etching. As shown in FIG. 6A,residue remained on the metal line after the photoresist was removed byoxygen plasma ashing. The wafer was then processed by immersion inComposition B as described above at 65° C. for 30 minutes. As shown inFIG. 6B, Composition B served to remove all the organometallic residuefrom the surface.

EXAMPLE 7

Example 7 illustrates the cleaning of a submicron circuit by means ofvia holes or openings, i.e., the holes on openings in the dielectriccovering layer on a substrate which allow access to conductive materialon the substrate, having a size of 0.6 microns on a silicon oxidedielectric layer which had been etched using a standard silicon oxideplasma etching processing. In particular, an oxide etcher as sold by LamResearch was utilized. In this process, the etching residue is mostlysilicon containing polymer with a small ratio of metal in thecomposition. The underlying layer was a metal substrate of TiN/Al—Si—Cu.The photoresist masking material was removed by oxygen plasma ashing.The substrate was then processed by immersion in Composition A asdescribed above for 30 minutes at 60° C. A cross-section micrograph froma scanning microscope as shown in FIG. 7A indicates that Composition Aremoved all the organometallic residue. As shown in FIG. 7B, however,residue remained inside the opening when an etched wafer processed inthe same conditions was treated in N-methyl-2-pyrrolidonesolvent/alkanolamine based stripper for 60 minutes at 90° C. in anultrasonic bath.

EXAMPLE 8

Portions of silicon oxide etching equipment which are made of heavygauge aluminum were removed from the etching equipment for cleaning. Theconventional procedure utilized to remove the deposited outgas residueon the etching equipment is by sandblasting. Sandblasting, however, is atime consuming procedure. It has been found that the residue depositedon the aluminum portion of the etching equipment can be easily removedby immersion in a composition of the present invention. An aluminumportion of etching equipment was immersed in Composition E for 30minutes at 40° C. Following rinsing and drying, it was observed that theresidue was removed.

EXAMPLE 9

The conventional process of cleaning a ceramic ring which forms a partof metal etching equipment involves either sandblasting or scrubbing byhand. Composition A was utilized to clean such ceramic ring by immersingthe ceramic ring in an ultrasonic bath for 45 minutes at 35° C. It wasfound that the deposits on the ceramic ring were completely removed.

EXAMPLE 10

Example 10 illustrates the cleaning of metal etch residue. AnAl—Si—Cu/W/TiW metal pattern sitting on a plasma enhanced TEOS wasutilized. The wafer had 50% overetching. P-5000 as sold by AppliedMaterial was used for the metal etching. The P-5000 is a single waferetcher and due to the processing technique of the etching equipment, ahigher build-up of polymer remains following the etching which is moredifficult to remove than that described in Examples 6 and 7 above. Asandwich metal substrate of Al—Si—Cu/W/TiW was patterned and etched inthe plasma metal etcher P-5000. The small amount of residue left on thecorner of the metal line after the photoresist was removed by oxygenplasma ashing and was cleaned using Composition B at 65° C. for 30minutes. Such cleaned substrate is shown in FIG. 8A. Composition B didnot provide for complete removal of the residue. A similar etched waferwas then processed by immersion in Composition D as described above at65° C. for 30 minutes. As shown in FIG. 8B, Composition D removed allthe organometallic residue from the surface. Composition B does notcontain a chelating agent and Composition D contains a chelating agent.It is surmised that the activity of Composition B had begun to decreasedue to its short term effectiveness based on the absence of a chelatingagent.

EXAMPLE 11

Example 11 illustrates that cleaning solutions containing chelatingagents have increased stability as compared to the cleaning solutionsnot containing chelating agents. Compositions A, C and G, as describedin Table I, were each placed in separate sealed Pyrex flasks andmaintained at room temperature for a period of 80 days. A sample wastaken from each flask at regular intervals and analyzed to determine itsactivity. The activity of the cleaning compositions is measured by thereduction potential of the hydroxylamine. It can be seen from FIG. 9that Compositions G and A, which does not contain a chelating agent,lost their activity much faster than Composition C.

Examples 16-29 below are further illustrative of cleaning solutionsprepared in accordance with the present invention. Examples 16-24describe cleaning solutions having long term effectiveness due to theinclusion of catechol or dihydroxybenzene as a chelating agent. Examples25-29 are illustrative of cleaning solutions which do not contain achelating agent and therefore have short term effectiveness.

The procedure utilized with respect to Examples 16-29 involved mixingthe composition components together followed by heating of the mixtureto 65° C. Wafer samples were then immersed in the cleaning solution for30 minutes with infrequent agitation. The wafer samples were then placedin a N-methyl-2-pyrrolidinone bath having a temperature of 80-85° C. for10 minutes. Thereafter, the wafer samples were rinsed in a water bath.In some of the Examples, the cleaning solution was subsequently dilutedby the addition of 20 parts water and fresh wafer samples processedtherein utilizing the same procedure for comparative purposes. The driedwafers were evaluated by an SEM spectrometer.

As used in the Examples, “DGA” stands for diglycolamine which is alsoknown as 2-amino-2-ethoxy ethanol, “DMSO” stands for dimethylsulfoxideand catechol is 1,2-dihydroxybenzene.

EXAMPLE 16

A cleaning solution including 35 parts hydroxylamine (50% aqueous), 27parts DGA, 5 parts catechol and 33 parts DMSO was prepared and utilizedto clean a wafer. The wafer had a polysilicon structure and wascompletely cleaned with no damage to the structure by the cleaningsolution. Wafers containing via holes also were cleaned of plasmaetching residue.

The cleaning solution was thereafter diluted with 20 parts water andfresh wafer samples cleaned utilizing the solution. The additional waterdid not reduce the ability of the solution to clean polysiliconstructures. The etching residue was satisfactorily removed from thewafer samples.

EXAMPLE 17

A cleaning solution containing 34 parts hydroxylamine (50% aqueous), 5parts catechol, 54 parts N-methyl-2-pyrrolidinone and 7 partstetramethylammonium hydroxide (25% aqueous) was prepared and utilized toclean wafers having a metal structure. The wafers were cleaned ofetching residue leaving no evidence of corrosion.

Thereafter, the cleaning solution was diluted with 20 parts water. Viaholes in the wafers were cleaned with the diluted solution leaving noevidence of undercutting the substrate.

EXAMPLE 18

A cleaning solution was prepared containing 35 parts hydroxylamine (50%aqueous), 59 parts DGA, 5 parts t-butylcatechol and 1 part water. Thesolution was utilized to clean wafers having a polysilicon structure.The wafers were cleaned without pitting of the substrate.

Thereafter, 20 parts water was added to the cleaning solution. Thediluted solution was utilized to clean fresh wafer samples. The dilutionof the cleaning solution did not diminish the cleaning effect of thesolution on polysilicon structures. Each of the solutions of Example 18were satisfactorily effective on via holes with no evidence ofundercutting of the wafer substrate.

EXAMPLE 19

A cleaning solution was prepared containing 35 parts hydroxylamine (50%aqueous), 45 parts DGA, 5 parts catechol and 15 partstetramethylammonium hydroxide (25% aqueous). The cleaning solutionprovided good cleaning of polysilicon structures with no pitting of thesubstrate.

EXAMPLE 20

A cleaning solution was prepared containing 60 parts DGA, 5 partscatechol and 35 parts N,O-dimethyl-hydroxylamine (50% aqueous). Thecleaning solution provided good cleaning of polysilicon structures andshowed very satisfactory results in the cleaning of via holes.

Thereafter, the cleaning solution was diluted with 20 parts water andutilized to clean fresh wafers. Dilution of the cleaning solution didnot diminish the cleaning ability of the solution.

EXAMPLE 21

A cleaning solution was prepared containing 51 parts DGA, 5 partscatechol, 31 parts methoxylamine hydrochloride and 13 parts water. Thecleaning solution cleaned metal structures leaving no corrosion on thestructures.

Subsequently, when 20 parts water was added to the cleaning solution todilute the solution, the diluted solution was found to clean polysiliconand via hole features with no apparent corrosion of the metal structure.

EXAMPLE 22

A cleaning solution containing 60 parts DGA, 5 parts catechol and 35parts N,N-diethylhydroxylamine was prepared. The cleaning solutioncleaned metal structures with no apparent corrosion of the structures.

When the cleaning solution was diluted with 20 parts water, the solutionadequately cleaned via holes and metal structures.

EXAMPLE 23

A cleaning solution was prepared containing 61 parts DGA, 5 partscatechol and 34 parts acetohydroxamic acid. The cleaning solutionprovided acceptable polysilicon wafer cleaning.

Subsequent dilution of the cleaning solution with 20 parts water did notaffect the ability of the solution to clean via hole structures inwafers.

EXAMPLE 24

A cleaning solution was prepared containing 60 parts DGA, 5 partscatechol, and 35 parts methylhydrazine. The cleaning solution providedgood results in cleaning wafer via holes.

Subsequent dilution of the cleaning solution with 20 parts water did notsignificantly diminish the solution's ability to clean via holes havingplasma etch residues thereon.

EXAMPLE 25

A cleaning solution containing 49 parts DGA, 4 parts catechol, 29 partsmethylhydrazinocarboxylate, and 18 parts water was prepared. Thecleaning solution was effective for cleaning polysilicon and via holestructures.

EXAMPLE 26

A cleaning solution having short term effectiveness was preparedcontaining 35 parts hydroxylamine (50% aqueous), 60 parts DGA and 5parts dimethylgloxime. The cleaning solution, when used just subsequentto its preparation, provided acceptable results for cleaning via holes.

When 18 parts water was subsequently added to the cleaning solution, viaholes were still effectively cleaned of plasma etch residue by thediluted solution.

EXAMPLE 27

A cleaning solution containing 60 parts DGA and 40 partsN,O-dinethylhydroxylamine (50% aqueous) was prepared. When utilizedimmediately following preparation of the solution, the cleaning solutioncleaned polysilicon structures with no problem.

EXAMPLE 28

A cleaning solution containing 53 parts DGA, 33 partsN-methylhydroxylamine hydrochloride and 14 parts water was prepared. Thecleaning solution, when used immediately following preparation of thesolution, cleaned polysilicon structures and via holes with nodetrimental effect.

EXAMPLE 29

A cleaning solution was prepared containing 60 parts DGA and 40 partsN,N-diethylhydroxylamine and 20 parts water. The cleaning solutioncleaned polysilicon structures with no corrosion resulting when thesolution was utilized immediately following its preparation.

EXAMPLE 30

A cleaning solution was prepared containing 60 parts DGA, and 40 partshydroxylamine (50% aqueous). The cleaning solution adequately cleanedpolysilicon structures, via holes and metal structures. However, afterapproximately one week, the solution lost its effectiveness although thecomposition had not changed. Five parts catechol were then added to thesolution and the solution reactivated. The reactivated solution was ableto again clean wafer structures, including via holes.

Upon diluting the reactivated cleaning solution with la parts water, thecleaning ability of the solution was found to be undiminished.

From the various test results set forth in the Examples, it can be seenthat the cleaning solutions of the present invention provide novel andsurprising results. The composition allows for a simple method of useand is adaptable to various modifications while still providing thedesired results. The composition of the invention therefore allows forbroad application upon minor adjustments.

As will be apparent to one skilled in the art, various modifications canbe made within the scope of the aforesaid description. Suchmodifications being within the ability of one skilled in the art form apart of the present invention and are embraced by the appended claims.

1-19. (canceled)
 20. A method for replenishing a resist and etchingresidue removal composition comprising adding a chelating agent to saidcomposition after said composition has been used to remove resist andetching residue, wherein said compositions consists of: hydroxylamine ora derivative thereof having a general formula of:

wherein R₁, R₂, and R₃ are independently hydrogen; a C₁-C₆ straight,branched or cyclo alkyl, alkenyl, or alkynyl group; an acyl group; astraight or branched alkoxy group, amidyl group, carboxyl group,alkoxyalkyl group, alkylamino group, alkylsulfonyl group, or sulfonicacid group; or a salt thereof, wherein chelating agent is added to acomposition that previously contacted a semiconductor substrate.
 21. Themethod of claim 20, further adding water to said composition after saidcomposition has been used to remove resist and etching residue.
 22. Themethod of claim 20, wherein the composition further comprises at leastone solvent which is miscible with the hydroxylamine or a derivativethereof.
 23. The method of claim 20, wherein the composition isreactivated with about 5 percent by weight of the chelating agent. 24.The method of claim 20, wherein the hydroxylamine or derivative thereofcomprises hydroxylamine.
 25. The method of claim 23, wherein thechelating agent added for replenishment is catechol and further addingup to about 18 percent by weight water to said composition after saidcomposition has been used to remove resist and etching residue.
 26. Themethod of claim 20, wherein the resist and etching residue removalcomposition consists of: (1) from about 5% to about 50% by weight ofhydroxylamine; (2) from 10 to about 80 % by weight of one or moreorganic solvents; (3) water; (4) from about 5% to 30% by weight ofchelating agent(s) comprising at least one of: (i) one or morehydroxy-functional compounds of formula II:

wherein n=1-4, m=2-5, and each R is independently hydrogen; a C₁-C₆straight, branched or cyclo alkyl, alkenyl, or alkynyl group; an acylgroup; a straight or branched alkoxy group, amidyl group, carboxylgroup, alkoxyalkyl group, alkylamino group, alkylsulfonyl group, orsulfonic acid group; or a salt thereof; (ii) thiophenol, a derivativethereof, or both, each of formula III:

wherein R₁₇ is OH or COOH; (iii) an ethylene diamine tetracarboxylicacid, a derivative thereof, or mixture thereof, each of formula IV:

wherein R₁₈, R₁₉, R₂₀ and R₂₁ can individually be H or NH₄; and (iv) oneor more alkyl ammonium hydroxides of the formula V, (R₁₁R₁₂R₁₃R₁₄)NOH,wherein R₁₁, R₁₂, R₁₃, and R₁₄ are the same or different and comprisealkyl groups having from 1 to 5 carbon atoms.
 27. The method of claim26, further adding water to said composition after said composition hasbeen used to remove resist and etching residue.
 28. The method of claim26, wherein the composition is reactivated with about 5 percent byweight of the chelating agent.
 29. The method of claim 26, wherein thechelating agent added for replenishment is catechol.
 30. The method ofclaim 28, wherein the chelating agent added for replenishment iscatechol and further adding up to about 18 percent by weight water tosaid composition after said composition has been used to remove resistand etching residue.